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At what point(s) do you collect prop samples for micro analysis before pitching?

What Media do you use to look for spoilage organisms during propogation phase and what are typical incubation times?

How many generations are you able to get out of your yeast propagating it this way and how often do you re-culture your slants/yeast sources?

These were the only points I would suggest to include, but a very good write up overall.

I would suggest number of generations is limited only by viability, and fermentation characteristics? It sounds like you use a lot of strains, so I would guess you typically don't stretch the generations to their full potential? Probably make slurry more often, since you have the ability?

I am looking at bringing yeast propagation in house, and have been doing quite a bit of research over the last 2 weeks, so i appreciate the post, but have a few questions:

1. At what point(s) do you collect prop samples for micro analysis before pitching?

2. What Media do you use to look for spoilage organisms during propogation phase and what are typical incubation times?

3. I am considering supplementing olive oil (in addition to shaker tables) into wort to help with yeast building up cell mass during early stage of prop (10ml-10L), but was wondering if that would cause the yeast to loose some of the genes early on for aerobic respiration (not familiar with yeast genetics enough to know unfortunately) and was wondering if you or anyone else on this forum had experimented around with it. Link to article explaining this here:

4. How many generations are you able to get out of your yeast propogating it this way and how often do you reculture your slants/yeast sources?

1. really any time possible after the first day.

2. BMB(mike barney miller agar) and UBA as well as LWYM (3711 french saison grows on this BTW)

tests take 7 days. PCR is expensive then you need good primers anyway. So it would be known after the fact if something went wrong, but at least you can stop it before packaging which is a huge loss

3. I've heard of the sterol oil treatment actually saw it first in a paper by New Belgium. From what I've read on the oil/aeration thing it's best to continue to aerate and avoid the oil. The patco anti-foam that's hydrogenated oil based not silicone apparently helps with the cell wall sterols and I suggest the use of anti foam in the prop anyway.

4. realistically about 10 the big problem was brew scheduling and being able to juggle it into active fermentations then harvest it without it sitting around waiting for more than a day or two. What killed the yeast being used 10+ times wasn't related to quality control most of the time.
honestly I would get LHBS vials/smack packs and make my own streak plates then isolate colonies that way. You would be surprised what contaminants grow on the plates you streak from a home brew vial on. I also didn't have access to a flow hood so sterile technique was a bit relying on ancient technology

The other brewery I worked at would push yeast 20-30+ generations and didn't propagate at all. But they also had a very efficient and predictable brew schedule and was able to harvest yeast completely aseptic with no exposure to the atmosphere at any point.

500mL media bottles were used to collect and autoclave the wort. the flasks were autoclaved separately with their stoppers on a dry cycle. then the sterilized wort is transferred into the flasks leave the trub behind

Propagating from Yeast Lab Pitch industry standard

Yeast,

Fabulous post!

We are a smallish brewery with fairly large fermentation tanks so we want to grow up our pitches that we buy locally. We do not have a lab nor time available to propagate using flasks. Basically, we want to skip the beginning steps of your SOPs and get right into the 3 bbl propagator.

We just acquired a 200 gal. tank that we want to dedicate as a yeast propagation vessel. We have HEPA air filters and will attach an aeration stone to the bottom outlet.

Question: If we buy industry standard pitches from our local yeast lab at 7 mill. cells / ml and pitch 4 liters of that into 100 gallons of 12 P. wort (with aeration), can we expect the same 10 fold increase in cell count that you got from your higher density 4 L pitches? If not, what kind of cell density can we expect using these types of pitches?

We are a smallish brewery with fairly large fermentation tanks so we want to grow up our pitches that we buy locally. We do not have a lab nor time available to propagate using flasks. Basically, we want to skip the beginning steps of your SOPs and get right into the 3 bbl propagator.

We just acquired a 200 gal. tank that we want to dedicate as a yeast propagation vessel. We have HEPA air filters and will attach an aeration stone to the bottom outlet.

Question: If we buy industry standard pitches from our local yeast lab at 7 mill. cells / ml and pitch 4 liters of that into 100 gallons of 12 P. wort (with aeration), can we expect the same 10 fold increase in cell count that you got from your higher density 4 L pitches? If not, what kind of cell density can we expect using these types of pitches?

Thanks for any input!

Two issues right off the bat.
Can you trust the standard pitches you buy? Propagation was brought to the table to get away from problems with bought pitches.

The other problem is inoculation of the prop tank with the bought pitch. Good luck achieving a completely aseptic transfer of all the bought yeast into the prop.
At least the prop is aerobic so you won't necessarily grow anaerobic organisms, but wild yeast or even other brewery yeast can become an issue.
This is why I went through the hassle of the lab side prop steps from dishes to flasks.

Our tank has a 6" TC opening on the top so my plan is to pour the 4 liters in through that opening. We'll try the flame method you showed in your photos.

Also now considering running a small march pump as a recirculation method for a day or two after aerating for 24 hours.

best of luck. It wouldn't be a bad idea to wear some gloves and a "I have the flu" face mask for this task. having a torch running in the area is a good idea just be careful about its location, don't melt anything. Even plastic bottles can have their openings flamed briefly.